Integration Depth Ladder

Integration Depth Ladder ranks e-commerce tools by how deeply they touch client data and workflows, not by feature lists. Rung one is surface: a chat widget or review app reading order history. Rung two is transactional: a cart recovery or subscription layer writing to checkout and payment events. Rung three is systemic: a search or commerce engine that owns product data, pricing logic, and post-purchase flows. Agencies should price and staff each rung differently, because a rung-three deployment carries migration cost and lock-in risk that a rung-one widget never does. The ladder also explains why overlapping tools bloat stacks: two rung-two vendors often duplicate the same checkout hooks. A concrete example is the contrast between SureCart, which replaces several WordPress plugins with one checkout and subscription layer, and a lightweight review app that only reads order data. The higher the rung, the more the agency's retainer depends on integration work rather than tool licenses.